Firstly there is only one entry for Tmax 400 on the Massive dev chart and secondly it gives the same times for both 400 and 800 Microphen, I went to the Ilford website and on the PDF for powder developers it doesn't even give times for Tmax 400 in Microphen 1+1, only 400 surly I don't have to use stock to do a push It's not cheap and I can get this to do 5 films if I dilute it 1+1.
Actually, using it stock is more economical: you can reuse the developer. I develop 10 films in 1L of microphen...only thing is that you have to think about adjusting the developing time for subsequent films...(+10% x the number of films developed previously).